Other mistake: When Deckard visits the Tyrell Corporation, he prepares to test Rachel with the "VK" machine. He is shown putting his briefcase of the table and lifting the "VK" machine out and onto the table. If you look closely, the "VK" machine is already on the table and Harrison Ford is miming the lifting - there is nothing in his hands!
Audio problem: Deckard (Harrison Ford) investigates the maker of artificial reptiles; an Abdul somebody. It's obvious that the dialogue was added as neither actor is in sync with the sound. The end of the scene has the storekeepers voice telling Deckard the information he was seeking while Deckard's mouth is the one moving. Deckard's mouth continues to move even after Abdul's lines are finished and the scene cuts. This has been corrected in the 2007 Final Cut of the film, but exists in all previous versions.
Continuity mistake: When Decker shoots the snake-woman replicant, she hits the glass and in one shot you can clearly see that is not the actress that hits the glass, but a stuntperson dressed like her. This has been corrected in the 2007 Final Cut of the film, but exists in all previous versions.
Trivia: In the scene where Daryl Hannah is startled by William Sanderson outside his home, she runs away toward his parked van and breaks a door window when she collides with it. If you look carefully you can see her slip off the wet curb at the same time. This was a real accident and Daryl Hannah continued with the scene because no one realized it at the time and Ridley Scott didn't yell,"Cut".
Deckard: I don't know why he saved my life. Maybe in those last moments he loved life more than he ever had before. Not just his life, anybody's life, my life. All he'd wanted were the same answers the rest of us want. Where did I come from? Where am I going? How long have I got? All I could do was sit there and watch him die.